It has become popular in recent years to manufacture home and office furniture items which include an internally mounted, power-driven elevator for supporting an appliance such as a television, television monitor, computer monitor or the like supporting an appliance, such as a television, television monitor, computer monitor or the like, and for selectively raising the appliance from within the furniture for use and lowering the appliance into the furniture for concealment when the appliance is not in use. Furniture incorporating such elevators is popular for use with large screen televisions such as those having plasmas or liquid crystal screens which are relatively thin. The elevators are typically electrically powered and are controlled by way of a manual switch mounted on or in the furniture and/or by a convenient handheld remote control unit, such as an infrared type, operable from some distance away. Furniture mounted appliance elevators having lift mechanisms using various types of drive units mechanically interposed between an electrical drive motor and an appliance support platform are known in prior art.
For example, U.S. Pat. No. 4,151,804 to Wache discloses an elevator in which a horizontal television support is vertically driven between raised and lowered positions by a threaded ball bearing nut threaded which engages a single, vertically-oriented, threaded rod which is rotatably driven by a belt drive train connected to an electric motor. In U.S. Pat. No. 6,494,150 to Phoenix et al. an elevator for a visual display includes a support connected at each end to one of a pair of threaded nuts. Each of the nuts engages a respective one of a pair of threaded vertical rods which are synchronously driven by a single electric motor coupled to both rods through a gear drive mechanism. The lifting mechanism disclosed in U.S. Pat. No. 6,733,094 to Chang also uses a pair of threaded vertical rods which engage correspondingly-threaded ends of a traverse bar that supports the screen to be lifted but uses a belt drive rather than a gear drive to rotate the threaded rods.
U.S. Pat. No. 5,129,611 to Grover et al. discloses a television display stand having intermediate and upper frames which telescope to extend vertically from the interior of a base frame by means of a series of pulleys engaging a cable wound about a rotatable capstan coupled to an electric motor through pair of bevel gears.
U.S. Pat. No. 6,612,670 to Liu discloses a screen elevating mechanism having a pair of vertical slide assemblies disposed between a of pair mutually-spaced, horizontal, traverse rods, the lower one of which is rotatable by means of a hand crank. Each slide assembly includes a transmission belt looped around the traverse rods and a screen bearer connected to each belt so that the screen bearers may be raised or lowered as the crank is turned manually.
U.S. Pat. No. 5,797,666 to Park describes a desk with a liftable monitor case. In one embodiment, the monitor case is lifted by a pantographic mechanism which is extended, to raise the monitor case, by drawing the ends of a pair of arms toward one another and retracted, to lower the monitor case, by moving those ends apart. To do so, and end of one of the arms is coupled to a nut bracket which engages a screw shaft driven by a reversible electric motor. In an alternative embodiment, the monitor case is driven by a rope and pulley mechanism.
Television elevator mechanisms which include four elongated racks, one of which is mounted in a vertical orientation at each of the four vertical corners of a parallel-piped shaped piece of furniture, are also known in the prior art. A horizontal shelf for supporting the television is supported at each of the four corners by a power-driven pinion gear which engages a respective one of the racks to vertically raise or lower the shelf, depending on the direction of rotation of the pinions.
The furniture industry is intensely competitive and cost sensitive. A shortcoming the prior art lift mechanisms described above is that each requires significant assembly in-situ within the piece of furniture in which it is to be installed. The time required to carry out such an assembly within the limited space available inside the furniture is not insubstantial and can significantly increase the labor costs borne by the furniture manufacturer. Those labor costs are increased, not only because of the actual time required to perform the assembly inside the furniture, but also by the necessity of having the work performed by installers having significant skill and training as well as manual dexterity. Installation skill and training specific to each particular type of lift mechanism used by the furniture manufacturer is required. Thus, training costs are multiplied if the furniture manufacturer uses several different types of lifts. The cost and time required to train installers limits the flexibility of furniture manufacturers to substitute lifts of one type for another or to begin use lifts of a different type in order to take advantage of lower prices, better quality, design improvements or more reliable sources of supply.
One prior art attempt to overcome such shortcomings is exemplified by U.S. Pat. Nos. 6,902,243 and 7,043,810 to Bober. That patent mounting a lift and its associated control module inside, and fastened to, a box-like sub-cabinet having at least three panels perpendicularly disposed about a floor panel. The sub-cabinet/lift/control module sub-assembly can then readily be inserted as a unit into a larger, decorative cabinet or other item of furniture. This arrangement simplifies installation and reduces installation time and cost by allowing the lift and its control module to be assembled and installed within the sub-cabinet before the sub-cabinet is inserted into the furniture. Being open on one or two sides, the sub-cabinet is less restrictive of the installer's reach and movements than the furniture into which the sub-assembly is subsequently inserted. The completed sub-assembly can be supplied to furniture manufacturers as a unit which can easily be inserted into a piece of furniture by workers having no special skill or training in assembling or wiring lift mechanisms. The mechanical details of the lift mechanism thus become largely irrelevant to the installation process thus permitting installation to be carried out by relatively unskilled workers. However, this approach has a number of significant drawbacks and limitations.
A sub-cabinet having at least three panels perpendicularly disposed about a floor panel, as taught by Bober '243 and Bober '810, occupies significant volume and is significantly heavier than a lift mechanism and its associated controls alone. Shipping completed lift/sub-cabinet/control module assemblies from a lift manufacturer to a furniture manufacturer therefore would entail significantly increased shipping expenses which would tend to erode, if not completely offset, the installation cost savings potential described above. Such sub-cabinets must also be of a 3-dimensional size compatible with the furniture in which they are to be installed. Ideally, the sub-cabinet would be only slightly smaller than the inside dimensions of a particular piece of furniture so to waste as little interior furniture space as possible. If so dimensioned for once particular piece of furniture, the same sub-cabinet would not fit inside a significantly smaller piece of furniture. Conversely, using the same sub-cabinet in a significantly larger piece of furniture would result in a significant waste of interior furniture space. Indeed, even under the ideal circumstance, a significant amount of interior furniture space would necessarily be lost owing simply to the thickness of the panels and floor forming the sub-cabinet. The material cost and assembly cost of the three or more panels which form the sub-cabinet is also commercially significant.